Hi All,

I recently purchased a like new 1993 W250 w/ auto and AC....Only problem is the brakes feel spongy when first applied and if you let off the pedal for a split second and get back on the brakes the pedal feels firmer and doesn't sink as low to the floor....Previous owner said it was the brake adjusters but I really didn't buy that.....He also said the master cyl was replaced 2 years ago......Anyways, I took the truck to the shop where I normally get reoairs done....They replaced the master cyl and repled the brakes.....Same problem.....They replaced the RAF (??) valva and powerflushed the system .....Same problem! ......Is there something that is getting missed?.....I'm $400+ into the brakes and still have the same problem or... GULP.... is the mushy pedal on the first pump a cummins diesel thing (I had one of those GM 5.7s years ago and the quirk w/ that system was if you pushed hard and continued pushing hard on the brakes the pedal would go lower and lower....but on that system apparantly it was "normal".....Are my brake problems "normal" for a cummins?....Scary part was the shop said that before they replaced the RAF (??) valve I was effectively stopping w/ only my front brakes.....Aaarg....Any ideas?.....
Thanks in advance for any help before I talk to the shop again.
Andrew

 

All ya gotta do is UPGRADE the rear wheel cylinders to the 1 ton's and ADJUST the rear shoes and you'll be all 's...BIG differance.. and about 25 bucks at NAPA

 

Replacing the rear wheel cylinders and shoes with the ones for a one ton is a nice upgrade but if the shop hasn't MANUALLY adjusted the rear brakes, they're just throwing parts at your problem.

Hate to say it but the previous owner was probably right. On these trucks, the self adjusters didn't.

YOU can probably fix it by putting the rear up on jackstands and crawling under the back, removing the rubber plug at the bottom of the brake backing plate and using a screwdriver (or the special tool that they sell to adjust brakes) and tighten the adjuster on each side until the brakes just barely rub. After that, you should notice a major difference in the pedal.

It is possible that the rear shoes are shot and can't be adjusted any further but that's not likely unless you're getting a metal-on-metal sound. If that fixes the problem, don't count on the self adjusters to keep them in adjustment. Do it yourself every few thousand miles and you should be in good shape.

Good luck

 

http://dodgeram.org/index.html You might look around this site. There was a tsb about brakes wearing fast when loaded heavy most of the time and they went to a bigger shoe and wheel cyl. I don't know if it was listed specificlly for the 93 or not. It improved wear and the amount of pressure required on the pedal. My 93 pedal is a little soft and has been that way since I got it. If yours improves a lot by pumping the brakes the rears need adjustment. If it only helps a little they are ok, and should be having just had them done. By the way the 5.7 you had had hydroboost brakes and the pedal would give a lot on them because of the amount of pressure they could apply. We have normal vacuum assist on ours.

 

I agree with 12valve@heart, you've put in alot of money already. Do the adjustment he describes. The shop might assume that the self adjusters will work, but ours are notorious for not self adjusting. A good shop owner would know the quirks on common vehicles, and take care of it.

If you are unsure about the adjustment he describes, grab a haynes manual. There's no reason you can't do it yourself and save a bundle of $. Best 15 bucks you'll spend. (for the engine though, go to cummins).

There's a trick you can try to get the brakes to self adjust, but I can't say whether it will work on your truck or not, because I haven't done it. Get the truck going at about 20 mph in reverse and slam on the brakes hard. Worth a try, it's free!!

Best of luck with it!

 

Thanks guys.....I'll try the adjusters.....I really didn't think that was likely but I guess the second pump on the pedal must push the rear shoes out further making the pedal higher ?? That is interesting and I hope it works but it would really pain me if I really didn't have to spend all the $$ I already did.....I'll keep you posted when I get back to town (on a business trip now and truck is at the house).

Andrew

 

Andrew,

You're pretty much right on track. The master cylinder can only displace so much fluid per stroke so the first stroke pushed the rear wheel cylinders part way out but ran out of fluid before the shoes seated and thus felt spongy because only the front discs were applying. The second stroke pushes the wheel cylinders further out and seats the shoes solidly and thus feels more solid because now you're stopping with all 4 wheels . If the shoes and drums wear too far, it is possible to blow the pistons clean out of the wheel cylinders and lose your rear brake fluid but for this to happen, you'd have to be WAY out of adjustment and severely worn. Also, you'll notice that the e-brake pedal will come up and be more solid when the rear shoes are adjusted correctly.

Since the truck is new to you, never hesitate to ask for an opinion if you have a questions. The guys here are a wealth of knowledge and are willing to share it with you for free so you might as well make the best of it. I know that they've taught me a bunch in the couple of years that I've had my truck.

 

Uncleroty

You are correct I have done the same thing with mine and you can actualy here them. BUT it dosen't seem to tighten them up enough,I still adjust by hand every few thousand miles

 

standing at the rear of the truck facing the tailgate, mounted inside the left hand frame rail to the rear of the axle (may have to drop the spare) is some sort of abs pump? that may have to be cleaned or replaced. If you step on the brake pedal with out the truck running you may hear that thing making noises....

 

I cut my self adjusters after 3 brake changes. Each time I would pull it apart I noticed that they had come off from the starwheel. I would replace the pads, fix the adjusters. They never seemed to do much go so on the 4th fixing, I cut them. Now I just adjust about every 3000 miles or so. Whenever the pedal is getting to low for my comfort.

 

HI All,

Thanks for all the input so far....I just got the truck back from the shop again....The owner said they rebled and adjusted the rear brakes and he took the vehicle out for a test drive (They actually put on over 60 miles!!!)....Anyways....He concluded the brakes were fine so he called me to pick it up....Anyways, SAME PROBLEM! AARG.....It was almost 5 when I got it so I just drove it back home.....I guess they better be glad I don't work for the Post Office!
Anyways, the whole situation wouldn't be so bad BUT I did spend over $400 only to be back where I started from (Well OK there are some new parts BUT the reason I took the truck in in the first place is still there!!!)....What gives?....Any more ideas?.....I think I may just ask for some $$ back and take it to Tufft Brakes or something like that? What would you do ?
Thanks again
Andrew

 

Andrew,

First of all, that's quite a test drive. Makes you wonder where they went or what they did.

Anyway, how does the emergency brake feel? Is it solid after just a few inches or can you push it most of the way to the floor? If it's solid right away (and didn't used to be), they probably adjusted the rear brakes correctly. If it's low, they may have just done the ol' backup-and-hit-the-brakes adjustment in which case not only did they not manually adjust the brakes but I'd question if they know anything about these trucks.

If the first pump is still spongy and hitting the brake pedal a second time makes the pedal firm, I'd still tend to believe that it's in the adjustment.

You may want to attempt the adjustment on your own to see if the pedal can be improved. It's not difficult unless you don't know which end of the screwdriver to hold.

Wish that I could tell you more.